As compared with natural gut material, artificial sausage casings of two-dimensional fiber material accelerate the water loss associated with the maturing of the sausage. This phenomenom is frequently desired because it improves the economic efficiency of sausage production. However, predominantly in the range of higher qualities, there are types of sausage which demand slower maturing or in which a higher final moisture content is desired. For these types of sausage, natural gut has therefore hitherto been preferred. Moreover, it has hitherto not been possible with artificial sausage casings to adjust their influence on the rate of maturing in accordance with the type of sausage or the wishes of the producer.
An artificial sausage casing of the type mentioned at the outset has been disclosed (East German Patent Specification 71,469), which consists of close-mesh nettle fabric with an outer collagen coating, the fabric on the inside having its natural roughness due to the fibers projecting from the yarn. Before filling, the known sausage casing is soaked in water, which dries out during the maturing process, and is replaced by the fat and meat juice which originate from the sausage meat and which act like a protective layer around the sausage filling and enable the exchange of moisture and gases, necessary for the maturing process, to take place. The natural roughness of the fabric on the inside here has an advantageous effect on the adhesion to the sausage meat unless the latter has an excessively high fat content. In fact, the protein-containing meat juice absorbed by the fabric effects, after a certain degree of drying, an adequate bond to the surface enlarged by the fibers. A positive bond between the fibers projecting from the fabric yarn and the sausage meat does not result, because, with unchanged roughness of the textile material, the projecting fibers are too small and too soft for this purpose so that they are pressed more or less smoothly against the textile material by the sausage meat subject to the filling pressure. For this reason, adhesion between the sausage casing and the sausage meat is not established when the liquid absorbed by the casing from the meat contains a large quantity of fat which impairs the bonding effect. There is then a risk of the casing being detached from the sausage contents during the maturing and drying process, and thereby the goods can become unsaleable. A further disadvantage of the known sausage casing is that its moisture permeability is too high for some types of sausage. As mentioned above, some high-quality types of sausage demand a slow maturing process, because the release of moisture is reduced to a fraction. The known sausage casing is unsuitable for such applications.
Artificial sausage casings are also known which are impregnated with fat, oil or similar substances as a separating agent, in order to facilitate peeling of the sausage casing from the sausage contents.
However, it is not the aim of the invention to facilitate the separation of the sausage casing from the sausage contents, but its object is the provision of an artificial sausage casing, in which the influence on the rate of maturing of the sausage is adjustable in a controlled manner and which, in particular, also permits very slow maturing due to a low release of moisture.
According to the invention, this is achieved when the sausage casing has an impregnation with fat or wax and the roughness on the inside is formed by stiff fibers or filaments which, in the finished sausage, are positively anchored in the surface of the sausage meat. An embodiment with a fiber pile on the inside is particularly advantageous.
On the one hand, the invention is based on the concept of closing the flow and diffusion paths, which are otherwise available for the exchange of moisture, by the incorporation of fat in the sausage casing. By suitable choice of the degree of impregnation, the extent to which the exchange of moisture is reduced can then be determined. A controlled influence can thus be exerted on the rate of maturing of the sausage.
On the other hand, it has been found that the impregnation with fat alone does not give a useful result because it reduces the adhesion of the sausage casing to the sausage material so that the casing can be detached at some points as a result of the reduction in diameter, associated with maturing, of the sausage material. This is prevented by the fibers or filaments on the inside of the sausage casing being positively bonded to the sausage filling and thus compensating for the loss of adhesion caused by the impregnation with fat.
The experience gained with the above-described known sausage casing (East German Patent Specification 71,469) did not lead to the expectation that this means for obtaining the necessary bonding between the sausage casing and the sausage filling would be sufficient. In fact, it had been found that the roughness of the fabric, produced by the projecting fibers, favors the adhesion of the sausage casing to the sausage filling only if gluing of the protein due to the drying meat juice can take place at the casing, but that the roughness is useless if excess fat is present. This is confirmed by the known fact that detachment of the casing from the sausage filling is facilitated by impregnation of the sausage casings with fat (European Published Application 88,308; German Offenlegungsschrift 2,827,862). The fact that, in the known sausage casings, the fabric roughness does not improve the adhesion to the sausage filling when excess fat is present can be explained (with hindsight) in such a way that the fibers are pressed by the sausage filling against the fabric layer, so that they form a continuous surface which, although it has a larger specific area than a fabric freed from the free fibers and hence allows better protein gluing, makes it rather more difficult to obtain a positive bond with the sausage meat, because the depressions and openings which are present in the fabric and into which the sausage meat particles could penetrate and anchor themselves are covered by the superposed, pressed-on fiber layer.
The sausage casing according to the invention shows a fundamentally different behavior towards the sausage meat. Since the roughness on the inside of the sausage casing is not formed by soft fibers of nettle fabric, which, in the wet state, are pressed smoothly against the fabric surface by the filling meat, but is formed by fibers of sufficient inherent stiffness or by fiber bundles combined into filaments which, due to the bundling, have a greater stiffness and, due to the bonding into the fabric, have a main orientation directed transversely to the fabric surface, these fibers cannot readily be pressed against the fabric, or there is a higher probability for solid particles of the sausage filling to be incorporated between adjacent pieces of fiber or filament, which are at a mutual distance and project from the fabric, so that a positive bond is formed, the adhesion of which does not depend on surface adhesion, in contrast to the known sausage casings. The result is that the invention makes it possible to adjust the rate of maturing of the sausage by more or less extensive impregnation of the casing with fat, without the adhesion of the casing to the sausage filling necessarily being lost, even if large quantities of fat are absorbed.
The improvement in adhesion, effected by the pile, is the greater, the more pile fibers are available for anchorage in the filling meat and the higher the pile is. Therefore, the adhesion of the casing to the sausage material can readily be fixed by suitable choice of these parameters in accordance with the requirements, and particularly, if appropriate, as a function of the extent of the impregnation with fat. The pile is selected the higher and the denser, the more extensive the impregnation and, consequently, the more the adhesion is reduced. The properties of the fiber or filament material used can also play a role since some types of fibers have greater adhesion than others.